Note 8 - Investment Securities - Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investment securities available for sale, amortized cost	$ 1,577,311	$ 1,126,867
Investment securities available for sale, gross unrealized gains	584	11,075
Investment securities available for sale, gross unrealized losses	163,484	10,633
Securities available-for-sale	1,414,411	1,127,309
US Treasury Securities [Member]
Investment securities available for sale, amortized cost	242,510
Investment securities available for sale, gross unrealized gains	0
Investment securities available for sale, gross unrealized losses	1,110
Securities available-for-sale	241,400
US Government Corporations and Agencies Securities [Member]
Investment securities available for sale, amortized cost	68,712	86,475
Investment securities available for sale, gross unrealized gains	526	1,169
Investment securities available for sale, gross unrealized losses	126	135
Securities available-for-sale	69,112	87,509
Collateralized Mortgage-Backed Securities [Member]
Investment securities available for sale, amortized cost	1,001,832	886,614
Investment securities available for sale, gross unrealized gains	58	9,465
Investment securities available for sale, gross unrealized losses	140,402	7,414
Securities available-for-sale	861,488	888,665
Collateralized Mortgage Obligations [Member]
Investment securities available for sale, amortized cost	35,378	9,547
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	3,669	430
Securities available-for-sale	31,709	9,117
Corporate Debt Securities [Member]
Investment securities available for sale, amortized cost	228,879	144,231
Investment securities available for sale, gross unrealized gains	0	441
Investment securities available for sale, gross unrealized losses	18,177	2,654
Securities available-for-sale	$ 210,702	$ 142,018